Acquiring new trained skills?

Maybe I just missed it reading the new playtest packet, but where does it mention learning a new trained skill?

I see it talks about when you get to add a bonus as you level to one current trained skill, and the same paragraph does mention getting a new trained skill, but doesn't specify when that happens.

Thanks.

'But the discord of Melkor rose in uproar and contended with it, and again there was a war of sound more violent than before, until many of the Ainur were dismayed and sang no longer, and Melkor had the mastery.'